This invention relates to a braided suture exhibiting one or more improved characteristics, e.g., reduced tissue drag, reduced chatter, greater flexibility and/or better hand than a known, or "standard", suture of substantially equivalent size.
Sutures intended for the repair of body tissues must meet certain requirements: they must be substantially non-toxic, capable of being readily sterilized, they must have good tensile strength and have acceptable knot-tying and knot-holding (knot security) characteristics and if the sutures are of the absorbable or biodegradable variety, the absorption or biodegradation of the suture must be closely controlled.
Sutures have been constructed from a wide variety of materials including surgical gut, silk, cotton, a polyolefin such as polypropylene, polyamide, polyglycolic acid, polyesters such as polyethylene terephthalate and glycolide-lactide copolymer, etc. Although the optimum structure of a suture is that of a monofilament, since certain materials of construction will only result in a stiff monofilament lacking acceptable knot-tying and knot-holding properties, sutures manufactured from such materials are preferably provided as braided structures. Thus, for example, sutures manufactured from silk, polyamide, polyester and bioabsorbable glycolide-lactide copolymer are usually provided as multifilament braids. Commercial examples of such sutures include those marketed under the DEXON (Davis & Geck, Inc.,) and VICRYL (Ethicon, Inc.) brands.
Currently available braided suture products are acceptable in terms of their knot-tying and knot-holding properties. However, as removed from the package, they tend to be stiff and wiry and retain a "set" or "memory" such that at the time of use, it is usually necessary for the surgeon or assistant personnel to flex and stretch the suture to make it more readily handible. Furthermore, the surfaces of known sutures are perceptibly rough. Thus, if one passes one's hand or fingers along the braid, surface irregularities will be readily detected. The result of this rough surface is that the suture will exhibit tissue drag and/or chatter as it is drawn through tissue, characteristics which militate against smooth, neat, accurately placed wound approximation, the hallmarks of excellence in surgical practice.
In the case of one braided suture now on the market, due to the necessity of having to meet fiber strength requirements while at the same time retaining acceptable knot-tying and knot-holding properties, the suture is constructed from a greater amount of fiber and consequently is of larger diameter than the accepted industry standard.
It is an object of this invention to provide a braided suture possessing one or more improved characteristics, e.g., reduced tissue drag, reduced chatter, greater flexibility and/or better hand than that of a known, or "standard", suture of substantially equivalent size.
It is another object of this invention to provide a braided suture which exhibits significantly better knot security, e.g., expressed in terms of knot pull strength and/or loop pull strength, compared with the knot security of a standard suture of substantially equivalent size.
It is a particular object of the invention to provide a braided suture exhibiting one or more of the foregoing improved characteristics possessing a greater number of sheath yarns, a finer denier for the individual filaments making up an individual sheath yarn and a greater pick count for a suture of any given overall denier.